1.1 Background
3
and pesticides. Nevertheless, the principles outlined here also apply to other
aspects of water quality study, including those focused on atmospherically
deposited contaminants and on land-based pollution sources.
The first step in designing a surface-water-sampling program is to identify
one or more problems or questions that require information on water quality.
Common water quality problems include nutrient enrichment (from a variety
of causes); effects of atmospheric deposition (acidification, eutrophication,
toxicity); and effects of major disturbances, such as fire or pest infestations.
Once the problems or questions have been clearly defined, a sampling program
can be designed that addresses what to measure and where and when and how
to conduct the sampling. The selection of measurements should be tailored to
specific study objectives and to the study design, which guides the specifics of
field, laboratory, and data analysis approaches.
A variety of air pollutants have the potential to stress aquatic ecosystems
through contributions from the atmosphere to Earth’s surface. A major focus
of this book is on atmospheric pollutants that contribute to surface water acidification and eutrophication (nutrient enrichment). Both atmospheric S and N
have the potential to cause acidification. Atmospheric N can also cause eutrophication of aquatic ecosystems in which the N supply is limiting for algal or
plant growth. Sampling for atmospherically deposited toxic materials is also
addressed, but in less detail.
Many freshwaters in the United States are thought to be phosphorus (P)
limited (US Environmental Protection Agency [EPA] 2008). In such waters, addition of P would be expected to increase plant or algal growth, whereas addition
of N would not. Nevertheless, there are also freshwaters considered to be N limited or N and P colimited. Furthermore, nutrient limitation can vary with season.
Individual researchers and government entities collect and analyze data on
natural resource sensitivity to, and effects from, air pollution on aquatic and
NUTRIENT ENRICHMENT
In N-limited and N- and P-colimited aquatic systems, atmospheric N
deposition can influence algal growth, trophic state, and the distribution and abundance of diatoms and perhaps other aquatic species.
Lakes and streams that are wholly or partly N limited are most likely
to occur in remote regions with naturally oligotrophic surface waters
that have not received high levels of atmospheric N deposition in the
past. Within the United States, such lakes and streams are most common in the mountainous West.
3
and pesticides. Nevertheless, the principles outlined here also apply to other
aspects of water quality study, including those focused on atmospherically
deposited contaminants and on land-based pollution sources.
The first step in designing a surface-water-sampling program is to identify
one or more problems or questions that require information on water quality.
Common water quality problems include nutrient enrichment (from a variety
of causes); effects of atmospheric deposition (acidification, eutrophication,
toxicity); and effects of major disturbances, such as fire or pest infestations.
Once the problems or questions have been clearly defined, a sampling program
can be designed that addresses what to measure and where and when and how
to conduct the sampling. The selection of measurements should be tailored to
specific study objectives and to the study design, which guides the specifics of
field, laboratory, and data analysis approaches.
A variety of air pollutants have the potential to stress aquatic ecosystems
through contributions from the atmosphere to Earth’s surface. A major focus
of this book is on atmospheric pollutants that contribute to surface water acidification and eutrophication (nutrient enrichment). Both atmospheric S and N
have the potential to cause acidification. Atmospheric N can also cause eutrophication of aquatic ecosystems in which the N supply is limiting for algal or
plant growth. Sampling for atmospherically deposited toxic materials is also
addressed, but in less detail.
Many freshwaters in the United States are thought to be phosphorus (P)
limited (US Environmental Protection Agency [EPA] 2008). In such waters, addition of P would be expected to increase plant or algal growth, whereas addition
of N would not. Nevertheless, there are also freshwaters considered to be N limited or N and P colimited. Furthermore, nutrient limitation can vary with season.
Individual researchers and government entities collect and analyze data on
natural resource sensitivity to, and effects from, air pollution on aquatic and
NUTRIENT ENRICHMENT
In N-limited and N- and P-colimited aquatic systems, atmospheric N
deposition can influence algal growth, trophic state, and the distribution and abundance of diatoms and perhaps other aquatic species.
Lakes and streams that are wholly or partly N limited are most likely
to occur in remote regions with naturally oligotrophic surface waters
that have not received high levels of atmospheric N deposition in the
past. Within the United States, such lakes and streams are most common in the mountainous West.